Traction control device and traction control method

Abstract

The speed v of a motor driven body, the rotational speed ω and the actual torque value T m generated by the motor are acquired. Subsequently, unit ( 741 ) estimates the slip rate X of the drive wheels based on the movement speed v and the rotation speed ω. Further, unit ( 742 ) estimates the drive torque T d based on the rotational speed w and the actual torque value T m . Next, unit ( 743 ) calculates a limit value L for a torque command value T c based on the slip rate X and the drive torque T d . Further, unit ( 744 ) limits the torque command value T c using the limit value L, generates a torque setting value T s , which is sent to a motor drive system ( 900 ). As a result, it is possible to quickly realize control in accordance with changes in the road surface state, thus allowing safe travel while ensuring the needed drive power.

The invention claimed is: 
     
       1. A traction control device for a moving body having a driving wheel that is driven by a motor, the traction control device comprising:
 a movement speed acquisition part acquiring a movement speed of said moving body; 
 a rotational speed acquisition part acquiring a rotational speed of said driving wheel; 
 an actual torque value acquisition part acquiring an actual torque value generated by said motor; and 
 a control part performing limitation control of an operation of said motor, wherein 
 said control part comprises:
 a slip ratio estimation part estimating the slip ratio of said driving wheel on the basis of said movement speed and said rotational speed; 
 a driving torque estimation part estimating the driving torque of said driving wheel on the basis of a value that is obtained by subtracting a value that is the product of the value of the differential coefficient of said rotational speed and the value of the moment of inertia of said driving wheel, from said actual torque value; 
 a limit value calculation part calculating a limit value for the torque setting value on the basis of said estimated slip ratio and said estimated driving torque; and 
 a limiter part limiting the torque setting value on the basis of said calculated limit value, and 
 
 said limit value calculation part calculates the limit value so that, the smaller the estimated slip ratio is, the larger difference from the estimated driving torque becomes, and the larger the estimated slip ratio is, the smaller difference from the estimated driving torque becomes. 
 
     
     
       2. The traction control device according to  claim 1 , wherein
 said limit value calculation part calculates the limit value by multiplying the estimated driving torque by a value corresponding to the estimated slip ratio. 
 
     
     
       3. The traction control device according to  claim 1 , wherein
 said limit value calculation part calculates said limit value L according to equation (I) below, using said estimated driving torque T d , said estimated slip ratio λ, and a constant a and a limiter coefficient k, the constant a and the limiter coefficient k having been determined in advance:
     L=T   d ·( a+k /λ)  (I).
 
 
 
     
     
       4. The traction control device according to  claim 1 , wherein
 said limit value calculation part calculates said limit value L according to equation (II) below, using said estimated driving torque T d , said estimated slip ratio λ, and a constant b and a limiter coefficient k 11 , the constant b and the limiter coefficient k 11  having been determined in advance:
     L=T   d *( b+k   11 /λ 2 )  (II).
 
 
 
     
     
       5. The traction control device according to  claim 1 , wherein
 said limit value calculation part calculates said limit value L according to equation (III) below, using said estimated driving torque T d , said estimated slip ratio λ, a constant c and limiter coefficients k 21  and k 22 , and the rate of change with time (dλ/dt) of said estimated slip ratio λ, the constant c and the limiter coefficients k 21  and k 22  having been determined in advance:
     L=T   d ·{( c+k   21 /λ 2   −k   22 ·( dλ/dt )}  (III).
 
 
 
     
     
       6. The traction control device according to  claim 1 , wherein
 the number of said driving wheels is plural; and 
 said limiter part calculates a torque setting value for all of said plurality of driving wheels on the basis of the minimum value of limit values that have been calculated for each of said plurality of driving wheels. 
 
     
     
       7. A traction control method that is used by a traction control device for a moving body having a driving wheel that is driven by a motor, comprising the steps of:
 acquiring a movement speed of said moving body, a rotational speed of said driving wheel, and an actual torque value generated by said motor; and 
 performing limitation control of an operation of said motor, wherein 
 said performing limitation control step comprises:
 estimating the slip ratio of said driving wheel on the basis of said movement speed and said rotational speed; 
 estimating the driving torque of said driving wheel on the basis of a value that is obtained by subtracting a value that is the product of the value of the differential coefficient of said rotational speed and the value of the moment of inertia of said driving wheel, from said actual torque value; 
 calculating a limit value for the torque setting value on the basis of said estimated slip ratio and said estimated driving torque; and 
 limiting the torque setting value on the basis of said calculated limit value, and 
 
 in calculating the limit value step, said limit value calculation part calculates the limit value so that, the smaller the estimated slip ratio is, the larger difference from the estimated driving torque becomes, and the larger the estimated slip ratio is, the smaller difference from the estimated driving torque becomes. 
 
     
     
       8. A recording medium, wherein a non-transient computer readable medium having recorded therein a traction control program that, when executed, causes a calculation part to execute the traction control method according  claim 7 .